Electric motors used to power blowers in Automotive Heating, Ventilation, and Air Conditioning (HVAC) systems benefit from cooling air flow directed through the motor itself. It is known to provide circular holes in the dome or hub portion of a centrifugal fan to allow cooling air to pass through the electric motor driving the fan. This cooling air flows internally through the motor to remove heat generated by brushes, coils, and/or electronic control elements so that the motor runs efficiently and with reduced degradation. However, circular holes often create a noise which has a frequency related to the number of holes as they pass a high pressure area developed at the inlet area of the fan. The noise can propagate through the HVAC system as noise heard by a person such as a passenger in an automobile. It is therefore desirable to have openings in the fan for cooling the motor that do not cause noise.